Work machines are commonly used to move heavy loads, such as earth, construction material, and/or debris. These work machines, which may be, for example, wheel loaders, excavators, bull dozers, backhoes, and track loaders, typically include different types of work implements that are designed to perform various moving tasks.
During the course of ordinary operation, it is often necessary for a work machine to move about a work site after its work implement has been raised to an elevated position. For example, when a wheel loader is removing earth, debris, or other material from a job site, the wheel loader may need to travel between a loading site and a dumping site. At the loading site, the wheel loader may load material into its bucket when the work implement is in a lowered position. The wheel loader may then raise the bucket to an elevated position and travel to the dumping site, so that the bucket can be positioned over a dump truck, or other removal vehicle. The wheel loader may then dump the material from the bucket into the dump truck and return to the loading site to repeat the process.
Depending upon the job site, the work machine may need to travel over terrain that is rough or uneven when moving between the loading site and the dumping site. Typically, the work machine includes two or more axles that pivotally support a frame or chassis. The rough or uneven terrain may cause the chassis of the work machine to pivot with respect to the axles. The pivoting, or oscillations, in the chassis results in a lateral rocking of the work machine as the work machine moves over the rough terrain. The magnitude of the oscillations may be increased when the work machine is carrying a load in the elevated position.
Because the cabs of the work machines are typically elevated to provide the operator with a better view of the job site, the operator is usually very sensitive to these oscillations. If the oscillations rise above a certain magnitude or reach a certain frequency, the operator may sense that the work machine is unstable. Under these circumstances, the operator may reduce the size of the carried loads to reduce the magnitude of the oscillations and restore a feeling of stability in the work machine. When the operator reduces the size of the loads carried by the work machine, the efficiency of the work machine is decreased accordingly.
The current trend in waste removal vehicles, such as dump trucks, is to increase the height of the vehicles. To compensate, the work machines will need to raise their loads higher to dump material into the waste removal vehicles. As the height of the load increases, so does the likelihood that the work machine will experience oscillations when traveling over rough terrain.
To improve the stability of a work machine and decrease the magnitude of oscillations, several factors on the work machine may be modified. For example the size of the wheel base, i.e. the distance between the wheels may be increased. However, in many cases, the width of the work machine may not exceed the width of the work implement. Thus, there are limits to the amount by which the width of the work machine may be increased.
The work machine may also be equipped with a shock absorbing or damping system to reduce the effects of traveling over rough or uneven terrain. One example of a damping system is described in U.S. Pat. No. 5,149,131. However, these system are typically designed to reduce the effect of a shock to both wheels on an axle and will not reduce or prevent lateral rocking of the work machine.
The damping system of the present invention solves one or more of the problems set forth above.